Image-capture device

ABSTRACT

An image-capture device includes an enclosure, a lens arranged in a lens housing, an illumination source and an image sensor. The illumination source has separately energized light emitters adjacent to the lens housing. When a first light emitter is energized, light oscillating in a first orientation is directed away from the image-capture device. When a second light emitter is energized, light oscillating in a second orientation different from the first orientation is directed away from the image-capture device. Alternatively, an image-capture device includes image sensors, a lens and an illumination source. The illumination source directs emitted light away from the device in different orientations. Light reflected from a subject-of-interest is received in optical paths intersected by respective polarizers. Reflected light passing through a first polarizer is substantially orthogonal to reflected light passing through a second polarizer.

TECHNICAL FIELD

This invention relates, in general, to photography, photogrammetry andassemblies used for capturing image information of subject matteroutside a studio.

BACKGROUND

Photogrammetry-derived virtual environments for use in virtual reality(VR), museum exhibits, video games, and digital cinema are limited toscenes featuring fixed light sources, such as the sun which, in thecontext of this application, is relatively fixed, and artificial lights.Since photogrammetry relies on sequences of overlapping photos takenfrom slightly converged angles, the implication is that fixed lightingsources produce shadows, specular reflections and for some materialssubsurface reflections that obfuscate the true color and surfacefeatures over portions of items in a scene. Fixed light sources cansimilarly influence data captured using other scanning methodologies.

Studio-based techniques for modeling objects are well-known. To date,such methods introduce an item before an image-capture system bound to alocation such as a studio or factory floor where an array of cameras andcontrolled artificial light sources, such as softboxes, light stages,light projectors, etc., are placed around the object.

For example, techniques for modeling layered facial reflectionsconsisting of specular reflectance, single scattering, shallow and deepsub-surface scattering from the skin of a human face are illustrated anddescribed in U.S. Patent Application Publication Number 2009/0226049 A1to Debovec et al. (hereinafter referred to as Debovec). Parameters forappropriate reflectance models are derived from 20 photographs recordedin a few seconds from a single viewpoint in a studio environment.Debovec introduces image-capture systems that use a plurality of lightsources with controllable output intensities to produce sphericalgradient illumination patterns of a person's face. Both thesubject-of-interest and the light sources are stationary and generallylimited to the confines of a studio. Polarizing filters are arrangedadjacent to the light sources to polarize the light from the lightsources in a desired orientation. The system includes two or morecameras with a desired polarization adjusted manually. A light projectoris added to illuminate a desired portion of person's face. An imageprocessing system receives specular reflectance and diffuse reflectancedata from the cameras and calculates reflectance for the facial imagebased on a layered facial reflectance model. The systems and methodsdisclosed by Debovec are resource intensive and impractical forcapturing images and constructing models of scenes in a non-studioenvironment.

Images of real-world environments captured during daytime hours presentchallenges due to the presence of continuous sunlight, the possiblepresence of ambient light from artificial sources and flash sources whenused. Light from each of these sources combines under some operationalconditions. Artificial light is affected by its respective inversesquare distance from a subject-of-interest, while sunlight is not. Thecontribution from a flashtube or flashlamp, which release light energyover milliseconds, is mostly unaffected by shutter speed. However, acamera operator subsampling a continuous light source such as the sun orlight from an artificial light fixture, when working from anon-stationary platform, can adjust shutter speed until the shutter isfast enough so as not to introduce issues with temporal resolution.

Ambient continuous light from the sun and fixed and unfixed lightfixtures separate from a camera, will necessarily introduce fixedshadows in captured images, which are problematic to the development ofvirtual environments requiring computer graphics (CG) lighting. In thecase of a continuous artificial light source, such as a light-emittingdiode (LED) based strobe, which continues to release light energy for aslong as a power supply can continue to provide sufficient input power, aslower shutter speed enables more light to contact a photosensitivearray but with an increased likelihood of loss of temporal resolutionfor freestanding cameras.

To appear realistic, a virtual environment, even in the presence ofsimulated fixed light sources and fixed shadows, ideally adapts tochanges in the perspective of the observer relative to the scene.Specifically, specular information should change relative to changesbetween the observer and reflective surfaces of objects in the scene.Specular reflections are typically simulated with a diffuse shader in alayered arrangement under a specular shader. As disclosed by Debovec,additional layers can be included to simulate subsurface scattering oflight in partially translucent materials.

Images of real-world environments captured during nighttime hours or inlocations blocked from sunlight present challenges when ambient lightfrom artificial sources and flash sources are used to illuminate ascene. Known artificial lighting techniques for minimizing shadows incaptured images outside of a studio are problematic for a number ofreasons. Generally, there is difficulty in transporting, locating,coordinating and energizing artificial light sources outside a studioenvironment. Consequently, it is often the case that the combination ofnatural and artificial light provides insufficient light to accommodateadequate surface-of-interest coverage because of distance, lightabsorption or both. Under insufficient light conditions, a photographerwill increase exposure times and aperture and if possible move closer tothe surface-of-interest. However, these longer exposure timesnecessitate the use of tripods to stabilize the camera position. Whenthousands of images may be required to map a real-world scene it isimpractical to closely position a camera to a surface-of-interest,capture an image, then relocate and adjust a tripod to position thecamera for each subsequent exposure necessary to capture a real-worldscene.

To avoid the inconvenience and effort of transporting and positioning atripod for each exposure, one or more artificial light sources, such asstrobes, can be synchronized to a shutter mechanism to a minimum ofabout 1/125^(th) of a second for focal plane shutters on most digitalsingle lens reflex (DSLR) cameras. However, photography dependent onartificial lighting capable of anything less than millisecond enabledstrobe lighting, e.g., ambient light from the sun and fixed and unfixedlight fixtures, will introduce shadows in the captured images.

Specialized lighting is called for when collecting image information forgenerating virtual environments supporting realistic lighting effectswith regard to shifting specular reflections accompanying changes inperspective, shifting shadows accompanying any change in position andpossibly rotation of a virtual light source, as well as a host of otherchanges in the quality of specular reflections and shadows in responseto changes in as many parameters governing the physics of the virtuallight source, such as virtual reflectors, collimators, and diffusers.

Because the scanning of environments, especially those with manyoccluded surfaces, requires constant movement of the capture system inorder to avoid data shadows, portability of the system is a primaryconsideration. Lighting hardware with sufficient output to properlyexpose surfaces in an environment, as opposed to surfaces of a smallerobject within an environment, often implies wall current and bulky powersupplies, implying a compromise to portability and nuisance factordealing with power chords. Considering the sheer volume of photographsrequired for adequate coverage, use of lights on stands is highlyimpractical if these must be repositioned and adjusted whenever thecamera moves to a new position and is redirected, with the result thatthe lighting needs change accordingly.

The second problem with lights on stands is that they cast shadows. Themost effective and efficient workflow supporting realistic virtuallighting of a photorealistic virtual scene, wherein moving a virtuallight results in moving its cast shadows, is to avoid introducingshadows into the source photography. A ring strobe directs light that issubstantially on-axis with the center axis of the sensor, thus castingshadows behind subject matter, while at the same time providing a highlyportable form factor, the illumination source being fixed to the camera.

While an on-axis light source such as a ring light minimizes shadows, anon-axis light source exacerbates specular reflections. Prior arttechniques for reducing specular reflection use cross-polarizationfilters. That is, placing a first polarizer on the light source at 90°with respect to a second polarizer on the lens. However, the loss ofthrough light with thin-film polarizers leads to a combined filterfactor of upwards of 3.5 f-stops of available light at the image sensor.The f-number, f-stop number or relative aperture is a dimensionlessratio of the focal length of a lens to the diameter of the aperture. Thef-stop number provides a quantitative measure of lens speed. A doublingof the f-stop number halves the size of the aperture. Consequently, eachf-stop represents a doubling or halving of the light depending onwhether the aperture adjustment is increasing or decreasing the size ofthe opening. Thus, the use of cross-polarization introduces difficultiesin providing sufficient illumination over a practical image area andseparation distance between a subject or subjects of interest in anon-studio environment and the camera to achieve an adequate exposure atpractical shutter speed, sensitivity and aperture settings.

Light output for purposes of three-dimensional capture is frustrated bynumerous factors. To minimize shadows, emitters must be placed as closeto the periphery of the lens as possible. Adequate light output can beachieved with concentric rings of emitters, but with every concentricarray of emitters, the angle of incidence relative to the center axis ofthe lens increases, thus casting ever more shadows.

Various camera settings can be leveraged to compensate for inadequateillumination, but each variable runs up against severe constraintsimposed by the requirements placed upon photogrammetric data to beuseful. For instance, by decreasing shutter speed more light is allowedto strike the sensor for a longer period of time, but because of theneed for the capture system to remain highly portable, any movementintroduced during an exposure, such as with handheld photography orworking off any camera platform that isn't fixed, such as from poles,ropes, or a UAV, may result in useless data. Imagery lacking sharptemporal resolution compromises quality when such images are used forphoto projection mapping, and in the case of photogrammetry, such datais entirely useless as a photogrammetry engine searching for commonpoints of interest between overlapping photos has no hope of locking inon imagery plagued by motion blur.

Opening the lens aperture is used to deliver more available light tosensors, but here the softness in pixels, and thus their ruin for 3Dcapture, is often the result of the shorter depth of field accompanyinglower F-stops, quickly throwing nearby and more distance subject matterfor given focal plane out of focus. Lastly, digital cameras turn tohigher ISO values, driving up the gain of the sensor to boost the signalat a given illumination level. Boosting a signal, of course, also boostsnoise, the problem here being that noise is unsightly at best, and inthe case of photogrammetry, large grain size confuses an enginesearching for common points of interest.

A conventional and portable solution for reducing shadows is describedin U.S. Pat. No. 6,430,371 to Cho (hereinafter referred to as Cho),which integrates a ring light guide with a camera. The guide includes ahousing attached to the camera by way of an adapter insertion holehaving an axis that is coaxial with the lens of the camera. The ringlight guide irradiates light toward an object in a direction that issubstantially aligned with an axis of the lens of the camera. Chofurther describes adjusting the amount of light irradiated to the objectdependent upon a camera to object distance. However, the combinationdisclosed by Cho is limited to objects that are close to the lens. Chofails to show a combination that addresses light loss from crosspolarization that would apply to the capture of subject matter that maybe beyond a few feet away from the lens. Cho also describes a manualapproach to controlling polarization states, with emphasis oncross-polarization used to cut specular reflections on machine parts andhuman skin to return diffuse color. No route is described to also recordimages containing diffuse color and specular reflections, and moreimportantly in a form such data can be utilized to isolate specularreflections enabling computer graphics lighting in a lighting andrendering engine.

SUMMARY

An example embodiment includes an improved image-based 3D capturedevice. The image-capture device includes a device enclosure, a lens, anillumination source and an image sensor. The lens is arranged in a lenshousing supported by the device enclosure. The illumination source hasseparately energized light emitters arranged adjacent to the lenshousing. When a first light emitter is energized, the image-capturedevice directs light oscillating in a first orientation away from theimage-capture device. When a second light emitter is energized, theimage-capture device directs light oscillating in a second orientationdifferent from the first orientation away from the image-capture device.Reflected light passes through the lens and is converted by the imagesensor to a data asset.

In another example embodiment the improved image-capture device includesa device enclosure with at least two image sensors, a lens and anillumination source. The lens is supported by the device enclosure. Theillumination source directs light away from the enclosure such that thelens receives reflected light from a subject-of-interest and directs thereflected light in a first optical path having a first polarizer and ina second optical path having a second polarizer. The polarizers arearranged such that reflected light that passes through the firstpolarizer is substantially orthogonal to reflected light that passesthrough the second polarizer.

In still another example embodiment, an image-capture device comprisesan enclosure, light emitters, and first and second sets of imagesensors. The light emitters and the first and second sets of imagesensors are arranged along a surface of the enclosure. The lightemitters direct light oscillating in a first orientation in a directionsubstantially orthogonal to the surface of the enclosure. The first setof image sensors receive reflected light oscillating in the firstorientation. The second set of image sensors receive reflected lightoscillating in a second orientation substantially orthogonal to thefirst orientation.

BRIEF DESCRIPTION OF THE DRAWINGS

The systems and methods for capturing image information can be betterunderstood with reference to the following drawings. The components inthe drawings are not necessarily to scale, emphasis instead being placedupon clearly illustrating the involved principles.

FIG. 1 is a schematic diagram illustrating the electromagnetic spectrum.

FIG. 2 is a schematic diagram illustrating an exemplary real-world sceneto be recorded with an image-capture device using novel image-capturetechniques.

FIG. 3 is a schematic diagram illustrating an image-capture devicewithin a real-world scene including a surface-of-interest.

FIG. 4A is a schematic diagram of an embodiment of the image-capturedevice of FIG. 3.

FIG. 4B is a schematic diagram illustrating how an embodiment of theimage-capture device of FIG. 4A reduces the likelihood of shadows inimages.

FIG. 4C is a schematic diagram of an alternative embodiment of theimage-capture device of FIG. 3.

FIG. 4D is a schematic diagram of another alternative embodiment of theimage-capture device of FIG. 3.

FIG. 5 is a schematic diagram of an alternative embodiment of theimage-capture device of FIG. 3.

FIG. 6 is a schematic diagram of another example embodiment of theimage-capture device of FIG. 3.

FIG. 7A and FIG. 7B include schematic diagrams illustrating polarizationof light.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

In generating photorealistic models of complex real world environmentsthe image capture system is charged with providing a post-processingworkflow digital assets containing data that is both useful to aphotogrammetry engine employed to solve for geometry in scenereconstruction and provide usable texture data allowing a lighting andrendering engine to realistically simulate the diffuse color andspecular reflectance of surface materials. Both objectives, geometry andtexture, are best served by controlling polarization states of thelighting in the source photography.

The image capture device is configured to produce lighting forseparately recorded exposures that is co-polarized and cross-polarizedper image pair. The cross-polarized exposure contains only diffuse colorinformation that is substantially shadow-free, and the co-polarizedexposure contains diffuse color with specular reflections that is alsosubstantially shadow free.

As indicated, macro and close-up photographic techniques cannot beapplied to adequately illuminate and capture subject matter suitable toaccurately model the same in human-scale environments. An exposurecaptured as a result of such techniques fails to evenly illuminate asubject over the entire image plane. Evenly illuminated exposures arecritical to source photography used in 3D scene reconstruction frommultiple images and also using alternative scanning methodologies suchas laser and structured light in which evenly illuminated photos providetextures by way of projective texture mapping. As further indicated,known portable light sources introduce undesired shadows that obfuscatediffuse color and surface texture of items in a real-world scene that isassembled from photographs. In addition, conventional image processingtechniques do not provide sufficient information in a model that can beused to generate realistic specular reflectance under changing lightingconditions in a virtual environment. Moreover, conventional portablephotogrammetry includes no solution for capturing subsurface scatter ina model that can be used to support CG lighting in a virtual environmentrepresenting a real-world location. In light of the above shortcomingsimprovements are desired.

Images that include subject matter that was captured with across-polarized lighting condition or a cross-polarized exposure providea first two-dimensional data set or diffuse map that includessubstantially shadow-free diffuse color. The image information stored asa result of the cross-polarized exposure is substantially shadow freewhen the reflected light from a controlled light source is nearlyon-axis with the sensor that captures the cross-polarized image. Inaddition, the cross-polarized exposure or the image that results fromsuch an exposure is substantially free of specular reflections. Such animage includes no discernible bright or shiny spots generally white incolor that result from a mirror like reflection of a broad range of thevisible spectrum that encounters a surface or surfaces captured in theimage.

Images that include subject matter captured with a co-polarized lightingcondition or co-polarized exposure provide a separate two-dimensionaldata set or specular map with substantially shadow-free specular color.The image information stored as a result of the co-polarized exposure issubstantially shadow free when reflected light from a controlled lightsource is nearly on-axis with the sensor that captures the co-polarizedimage. Images, however captured, may be temporarily stored in a memoryin the improved image-capture device.

Alternatively, the images or image information may be communicated to anintegrated storage medium and/or to a remote storage medium as desired.

The phrase “ambient light” as used herein means electromagneticradiation from both natural and artificial sources that are notcontrolled by a camera or controller associated with a camera.

The phrase “artificial light” as used herein means electromagneticradiation from manmade sources.

The phrase “binned sensor” as used herein means an image sensor whereelectrical signals from two or more adjacent pixels are sampledtogether.

The word “camera” as used herein means a device for recording images.

The phrase “camera orientation” as used herein means the sensororientation in an image-capture system at the time of an exposurehowever or whenever determined.

The word “color” as used herein means the set of physical properties ofan object, namely electromagnetic radiation absorption, reflection oremission spectra.

The phrase “controlled light” as used herein means electromagneticradiation generated by a light source under the influence of an input.

The term “co-polarization” as used herein means emitting electromagneticradiation from a controlled source in a first polarization angle andreceiving reflected electromagnetic radiation at an imaging sensor inthe same polarization angle.

The phrase “co-polarized exposure” as used herein means the act ofintroducing electromagnetic radiation as determined by shutter speed andlens aperture from a controlled source in a first polarization angle andreceiving reflected electromagnetic radiation at an imaging sensor inthe same polarization angle where the imaging sensor converts theincident electromagnetic radiation to electrical signals in accordancewith a present image sensor sensitivity.

The term “cross-polarization” as used herein means emittingelectromagnetic radiation from a controlled source in a firstpolarization angle and receiving reflected electromagnetic radiation atan imaging sensor in a second polarization angle shifted +/−90° from thefirst polarization angle.

The phrase “cross-polarized exposure” as used herein means the act ofintroducing electromagnetic radiation as determined by shutter speed andlens aperture from a controlled source in a first polarization angle andreceiving reflected electromagnetic radiation at an imaging sensor in asecond polarization angle shifted +/−90° from the first polarizationangle where the imaging sensor converts the incident electromagneticradiation to electrical signals.

The phrase “diffuse color” as used herein means the set of physicalproperties of a subject or subjects of interest as visually perceived byreflection equally in all directions. Visually, this is the dull, notshiny, color isolated from specular reflections.

The phrase “diffuse map” as used herein means a texture map that assignscolor to a shader when the shader is processing data within the texturemap.

The phrase “digital asset” as used herein means data which is applied inan imaging process in a defined workflow.

The word “exemplary” as used herein means serving as an example,instance, or illustration. Any aspect described herein as “exemplary” isnot necessarily to be construed as preferred or advantageous over otheraspects.

The word “exposure” as used herein means the act of introducingelectromagnetic radiation, as determined by shutter speed and lensaperture, to a sensor that converts the incident electromagneticradiation to electrical signals in accordance with image-sensorsensitivity.

The word “freestanding” as used herein means not supported physically bya fixed structure or object.

The term “hyper-spectral” as used herein means an image sensor thatgenerates separate electrical signals in response to electromagneticradiation incident at the sensor in many frequency bands across theelectromagnetic spectrum. Frequency bands are not necessarily continuousand do not necessarily include frequencies visible to a human observer.When compared to the frequency bands of a multi-spectral sensor, thefrequency bands of a hyper-spectral sensor are smaller and greater innumber.

The phrase “image-capture device” as used herein means an apparatus thattemporarily stores respective images responsive to cross-polarized andco-polarized light received from a surface or surfaces controllablyilluminated.

The phrase “image-based three-dimensional capture device” as used hereinmeans a hardware system employing photography to capturethree-dimensional scan data and/or to provide texture data associatedwith three-dimensional scan data derived from an alternative scanningmethodology.

The word “light” as used herein means electromagnetic radiation bothvisible and non-visible to a human observer.

The term “multi-spectral” as used herein means electromagnetic radiationin at least four specific frequency bands. As used herein the specificfrequency bands are not necessarily adjacent to one another, may or maynot overlap one another, and may include frequencies visible to a humanobserver as well as frequencies non-visible to a human observer. Whencompared to the frequency bands of a hyper-spectral sensor, thefrequency bands of a multi-spectral sensor are larger and fewer innumber.

The phrase “orientation” as used herein means the location and directionin a three-dimensional coordinate system of an image-capture system.

The word “photogrammetry” as used herein means the science of makingmeasurements from photographs.

The word “polarizer” as used herein means a filter that substantiallyreduces the passage of electromagnetic radiation in other than a desiredplane.

The phrase “projective texture mapping” as used herein is a method oftexture mapping that enables a textured image to be projected onto ascene as if by a slide projector.

The phrase “reflected light” as used herein means electromagneticradiation from any source that is cast back from a surface orsub-surface.

The word “sensor” as used herein means an array of picture elements thatgenerates electrical signals in response to electromagnetic radiationincident at the corresponding picture elements.

The phrase “sensor orientation” as used herein means the location anddirection in a three-dimensional coordinate system of an image sensor inan image-capture system at the time of an exposure.

The phrase “specular color” as used herein means the set of physicalproperties of an object as visually perceived via reflection when theobject is illuminated by electromagnetic radiation from a source definedby intensity, frequency, distance, and an angle of incidence relative tothe normal surface of an object.

The phrase “specular map” as used herein means a two-dimensional dataset that includes specular color from one or more co-polarized exposuresor non-polarized exposures.

The word “studio” as used herein means a room where a photographer orvideographer works.

The phrase “three-dimensional capture” as used herein means any hardwaresystem used to collect three-dimensional data of an object or a surfacein an environment.

The phrase “three-dimensional scene reconstruction from multiple images”as used herein refers to the creation of three-dimensional models from aset of images. It is the reverse process of obtaining two-dimensionalimages from three-dimensional scenes.

The capture system serves to benefit the need to virtualize human-scaleenvironments, such as residential and commercial real estate, retailspaces, sensitive archeological sites, highly inaccessible locationssuch as caves, and remote geologic surface features, including distantplanets. While 3D capture of exterior environments is also valued,interior spaces are of special interest considering the constraintplaced upon capturing texture data by lighting requirements. Whilewindows provide for ambient sunlight, shadows and more generallyinadequate levels of ambient sunlight make for problematic conditions inthe attempt to record image data purposed either to 3D scenereconstruction from images or to providing textures as used inprojective texture mapping wherein a scene reconstruction was derived byan alternate scanning methodology.

The capture system also serves to benefit the need to virtualizeobjects, such as furniture, decorative objects, and any variety of otherobjects used to furnish and decorate virtualized environments or serveas props. While prior art can be used to capture textures of objects,the premium placed on portability in capturing environments serves as adouble advantage in capturing objects, in light of how impractical it isto transport objects to a studio for capture as disclosed by Debovec.For example, transporting a large piece of furniture to a studio addsconsiderably to the expense of capture, whereby a portable capturesystem can more easily travel to and set up at a warehouse or showroomand capture furniture in situ, with no need to even move the furniturefrom its location within the building. While the system and methoddisclosed by Cho may be relatively more practical to deploy to capturetextures of human-scale environments, Cho is impractical as it wouldrequire manually rotating a polarizer with every other image capture, aswell as the time consuming activities associated with outputting a videosignal used to monitor in real time the effect of changes incross-polarization and co-polarization to specifically target and dialin extreme states between each type exposure.

Independent of the application, whether for rendering virtualenvironments, for use in creating or editing a visual effect forbroadcast television, cable television, Internet streaming, digitalcinema, animations, VR, or video games, dynamic virtual or CG lightingbenefits from having as a starting point nearly pure or diffuse colordata in a separate channel from that associated with specular colordata. The separation of diffuse color data from specular color dataenables an image processor to render more realistic representations of avirtual environment when lighting conditions change.

When a light source moves in the real world an observer sees shadows andspecular reflections change accordingly. Similarly, when an observermoves in the real world, specular reflections and in the case ofpartially translucent materials, subsurface scatter changes from theperspective of the observer. Accordingly, it is a benefit when moving avirtual light in a virtual environment for an observer to see shadowsand specular reflections shift in accordance with changes in thelocation and orientation of the virtual light source. Likewise, when theperspective of the virtual observer is changing it is further beneficialfor specular reflections, and in the case of translucent materials, forthe behaviors of subsurface scatter to change in the virtualrepresentation.

As described in the technological background, photography that issubstantially shadow-free using conventional ring strobes alone isn'tenough to produce imagery that is well-suited for photogrammetry asspecular reflections appearing at different surface normal vectorswhenever the camera and strobe assembly change position and orientationchallenge a photogrammetry engine searching for common points ofinterest.

In contrast with conventional systems and as described in the exampleembodiments, the present image-capture devices combine substantiallyshadow-free lighting with photography to capture surface textures thatcan be used to isolate diffuse color data from specular color data. Thesurface or surfaces of interest at a location to be modeled areilluminated by a light source that provides sufficient light underdifferent polarization states to adequately expose photosensitiveelements in an image sensor. A set of diffuse maps may be used withconventional photogrammetry techniques to generate models of areal-world locations or scenes and of objects. Matched images or imagesof substantially the same subject matter exposed under differentlighting conditions are used to generate a modified image. This modifiedimage or isolated-specular surface texture is used as a separate inputwhen rendering a virtual environment from the model. Accordingly, a setof exposures captured at a location or of an object are temporarilystored as image files and processed using an image-processing techniqueto generate the modified image. An example of such an image-processingtechnique is described in U.S. application Ser. No. 14/953,615, filed onNov. 30, 2015 and titled “Systems and Methods for Processing ImageInformation” the contents of which are incorporated herein by reference.

Light emitted from an improved image-capture device substantiallyreduces and for some textures virtually eliminates shadows in the colorinformation. An illumination source and controller operate in responseto one or more signals from the image-capture device to illuminate asurface or surfaces of interest with a first polarization state suchthat reflected light incident at an optical subsystem of theimage-capture system passes through an open shutter and reaches an imagesensor where the light is converted to electrical signals that aretemporarily stored (e.g., in an image file). In addition, theillumination source and controller illuminate the same surface orsurfaces of interest with light having a second polarization state andpower level different from the first polarization state and power level.The first polarization state and the second polarization state areexamples of a desired polarization state.

An improved image-capture device includes an illumination source havingseparately energized light emitters. The light emitters are adjacent toa lens housing. When a first light emitter is energized, lightoscillating in a first orientation is directed away from theimage-capture device. When a second light emitter is energized, lightoscillating in a second orientation, different from the firstorientation, is directed away from the image-capture device.

Such an improved image-capture device further includes a sensor arrangedto convert reflected light to electrical signals responsive tocharacteristics of the reflected light and a controller. The controlleris in communication with the optical subsystem and the sensor. Thecontroller coordinates operation of the optical subsystem and theillumination source such that an interval between a first exposure ofthe sensor to light oscillating in the first orientation directed awayfrom the image-capture device and reflected by a subject of interest anda second exposure of the image sensor to light oscillating in the secondorientation directed away from the image-capture device and reflected bythe subject of interest is controlled.

In an example embodiment, the interval between the first exposure and asecond or subsequent exposure results in a first raster of imageinformation and a second raster of image information where the firstraster and second raster include substantially similar imageinformation. In such an example, the image information in the firstraster and the image information in the second or subsequent raster areresponsive to substantially the same orientation of the opticalsubsystem.

In an example embodiment, the controller generates a signal that whenreceived at the illumination source, directs the illumination source tomodify one of the first orientation or the second orientation.

In an example embodiment, the controller generates a signal that whenreceived at the illumination source, directs the illumination source tomodify an illumination power. When the light emitter or light emittersare semiconductor devices, the illumination power can be controllablyadjusted by modifying the magnitude of a bias current.

In an example embodiment, the first light emitter and the second lightemitter are arranged circumferentially about a lens housing of theoptical subsystem. In such examples, a distance along a planesubstantially orthogonal to a longitudinal axis of a lens housingbetween nearest neighbor semiconductors is determined by a minimumtolerance associated with a manufacturing process. Furthermore, in suchexamples the first and second light emitters are arranged with respectto the lens housing such that emitted light is prevented from enteringthe lens without contacting a surface of a subject of interest.

In an example embodiment, the first light emitter and the second lightemitter are further arranged to prevent emitted light from the firstemitter from passing through a polarizer filter associated with thesecond light emitter and respectively to prevent emitted light from thesecond emitter from passing through a polarizer filter associated withthe first light emitter.

In an example embodiment, the illumination source emits white light.

In an example embodiment, the illumination source emits invisible light.

In an example embodiment, the illumination source emits hyperspectrallight.

In an example embodiment, at least one of the first light emitter andthe second light emitter are formed from a ring of elements. Such a ringof elements is arranged concentrically about a lens housing of theoptical subsystem.

In alternative embodiments, at least one of the first light emitter andthe second light emitter include elements arranged in more than one ringsurrounding a lens. In such embodiments, a first substrate supports oneor more ring of elements, while a second substrate supports a respectiveone or more ring of elements. In these embodiments, the first substrateis offset from the second substrate in a dimension parallel to thelongitudinal axis of the lens housing of the optical subsystem. In someof these embodiments, the offset may be selected such that an emittingsurface of the respective elements distributed across a first ring and aconcentric ring are substantially coplanar. While described herein asseparate substrates, it should be understood that a single substratewith first and second substantially parallel surfaces can be used tosupport one or more rings of elements wherein emitting surfaces of therespective elements are substantially coplanar.

In an example embodiment, the illumination source directs lightoscillating in two orientations substantially orthogonal to one anotheraway from the image-capture device, the light forming an angle ofincidence with respect to a longitudinal axis of a lens housing of theoptical subsystem of less than about 2.5 degrees when reflected by asubject of interest separated by at least one meter from theimage-capture device.

In an example embodiment, the sensor includes semiconductors responsiveto hyperspectral electromagnetic radiation.

In an example embodiment, the sensor is nonplanar.

In an example embodiment, the first orientation is substantiallyorthogonal to the second orientation. Light oscillating in one of thefirst orientation or the second orientation may be responsive to arespective feature of one of the first light emitter or the second lightemitter. Alternatively, light oscillating in one of the firstorientation or the second orientation may be responsive to either afirst polarizer located between the first light emitter and a subject ofinterest or a second polarizer located between the second light emitterand the subject of interest, respectively.

In an example embodiment, the optical subsystem includes a polarizerconfigured substantially orthogonal to reflected light oscillating inone of the first orientation or the second orientation and substantiallyparallel to light oscillating in the remaining one of the firstorientation or the second orientation.

For example, when a polarizer is configured substantially parallel toreflected light oscillating in one of the first orientation or thesecond orientation, a relatively lower illumination power is provided toilluminate the subject-of-interest during one of the paired or relatedimage exposures. When a polarizer is configured substantially orthogonalto reflected light oscillating in one of the first orientation or thesecond orientation, a relatively larger illumination power is providedto illuminate the subject-of-interest (e.g., a surface or surfaces)during the remaining one of the paired image exposures.

In an alternative embodiment, an improved image-capture device includesan enclosure including two or more image sensors, an optical subsystemsupported by the enclosure and an illumination source. The opticalsubsystem includes two or more lenses that receive reflected light froma subject of interest. The reflected light is directed along first andsecond optical paths. The first and second optical paths encounter arespective polarizer and are arranged such that reflected light thatpasses through a first polarizer is substantially orthogonal toreflected light that passes through a second polarizer. In thisalternative embodiment, at least one image sensor intersects the firstoptical path and at least one separate image sensor intersects thesecond optical path.

In an example arrangement, the alternative embodiments briefly describedin the preceding paragraph may be augmented by a beamsplitter arrangedsuch that light in the first optical path traverses the beamsplitter andlight in the second optical path is reflected by the beamsplitter.

In the above described alternative embodiments, the illumination sourceand the optical subsystem are arranged to prevent emitted light fromentering the optical subsystem without contacting a surface of a subjectof interest.

In the above described alternative embodiments, the illumination sourcecomprises semiconductors arranged about a surface of the enclosure.

In the above described alternative embodiments, emitted light directedaway from the enclosure of the image-capture device is orthogonallypolarized with respect to a polarization angle of reflected light thatintersects at least one image sensor.

In the above described alternative embodiments, a first image sensorintersecting the first optical path captures a first image and a secondimage sensor intersecting the second optical path captures a secondimage such that the first image and the second image are captured at afirst time. Alternatively, a first image sensor intersecting the firstoptical path captures a first image at a first time and a second imagesensor intersecting the second optical path captures a second image at asecond time different from the first time.

The elapsed time between a first exposure and a second or subsequentexposure may be controlled by the image-capture device. That is, thecontroller synchronizes operation of the illumination source with thevarious electro-mechanical elements of the optical subsystem and asensor to generate a first exposure. Independent of the sequence, afirst exposure is the result of illumination of a subject-of-interest asthe result of a first illumination power and a second exposure is theresult of illumination of substantially the same subject of interestilluminated as the result of a second illumination power where thesecond illumination power is not necessarily the same as the firstillumination power. In some embodiments, the illumination controller maybe arranged to electronically enable or adjust a polarizer arranged in apath between a controlled light source and the scene-of-interest. Suchan electronically enabled adjustment may be applied to leverage theentire amount of available light.

In a preferred embodiment, whether the two exposures are co-polarized orcross-polarized, reflected light reaches the sensor in both exposures,and absent very fast relative movement between the subject matter beingimaged and the image-capture device, the paired images includesubstantially the same subject matter across the raster of pixels storedin separate image files.

In another alternative embodiment, an improved image-capture deviceincludes an enclosure, light emitters, and first and second sets ofimage sensors. The light emitters and the first and second sets of imagesensors are arranged along a surface of the enclosure. The lightemitters direct light away from the enclosure in a directionsubstantially orthogonal to the surface of the enclosure. This directedlight is oscillating in a first orientation. The first set of imagesensors receives reflected light oscillating in the first orientation.The second set of image sensors receives reflected light oscillating ina second orientation that is substantially orthogonal to the firstorientation.

In the alternative embodiment described in the preceding paragraph, thelight emitters are offset from the first and second sets of imagesensors to prevent light originating at the light emitters from directlycontacting the first and second sets of image sensors.

The image-capture device described immediately above may be furtheraugmented by a third set of image sensors arranged to receive reflectedlight oscillating in more than one orientation.

In an alternative embodiment, an image-capture system could be arrangedwith paired cameras. In such an arrangement a single camera orientationwould apply to the image pairs and would provide optimal inputs for adifference blend operation to isolate specular reflections from diffusecolor. A single emitter could be used in conjunction with a filmpolarizer to illuminate a subject-of-interest with polarized light. Afirst camera may receive the reflected light after it is furtherredirected by a beamsplitter. A second or “through-path” camera isprovided after the beamsplitter. A polarizer may be provided before theimage sensor in the through-path camera to partially balance theincident or reflected light lost in the beam splitting process. The useof multiple image sensors and a beamsplitter increases production costsand design complexity and likely introduces a calibration to balance thecorresponding image pairs. However, if the image sensors shifted out ofalignment, a global fix could be applied to the paired images.

Images that include subject matter that was captured with across-polarized lighting condition or a cross-polarized exposure providea first two-dimensional data set or diffuse map that includessubstantially shadow-free diffuse color. The image information stored asa result of the cross-polarized exposure is substantially shadow freewhen the reflected light from a controlled light source is nearlyon-axis with the sensor that captures the cross-polarized image. Inaddition, the cross-polarized exposure or the image that results fromsuch an exposure is substantially free of specular color or the shinycolor that results from reflectance that is free of specular color. Atone end of the spectrum, the more obvious example of specular color isthe shiny color in an image that results from reflectance off highlysmooth surfaces. Such an image includes no discernible bright or shinyspots generally white in color that result from a mirror like reflectionof a broad range of the visible spectrum that encounters a surface orsurfaces captured in the image. At the other end of the spectrum,there's the pure matte surface property than only reflects diffusecolor, and then there's the less obvious range of specular reflectanceproperty found in materials, this entire range of specular behaviorassociated with varying micro-surface roughness ending in pure glossyspecular reflection, this range characterized by what's commonlyunderstood to comprise the specular hardness value associated with aparticular specular reflection.

Images that include subject matter captured with a co-polarized lightingcondition or co-polarized exposure provide a separate two-dimensionaldata set or specular map with substantially shadow-free specular color.The image information stored as a result of the co-polarized exposure issubstantially shadow free when the reflected light from a controlledlight source is nearly on-axis with the sensor that captures theco-polarized image. The paired images are stored in a memory in theimproved image-capture system.

The present image-capture devices can be adapted and applied to afreestanding system for recording images of real-world scenes or objectsunder controlled lighting conditions. Such a freestanding image-capturedevice may be hand-held; temporarily attached to an adjustable pole;supported from above by way of a harness; suspended by a carriage ormember arranged on an elongate flexible member, such as, a cable, wire,filament, rope, etc., supported by respective poles or other structures;temporarily integrated with a land-based vehicle, a floating or buoyantvehicle, an underwater vehicle, a lighter than air vehicle or evenintegrated on other types of aerial vehicles. Accordingly, animage-capture device consistent with the present principles andtechniques is not necessarily stationary and can be in motion.

The present image-capture devices can be used to forward a set ofdiffuse images to a photogrammetry engine to generate a dense surfacemesh, which after post-processing delivers a render mesh. The rendermesh includes a three-dimensional model of the geometry of the subjectmatter captured in the images and a set of UV maps. The render mesh isused with camera orientation information and the surface textures tocreate corresponding diffuse maps. The render mesh and the diffuse mapsare inputs that can be used by an image processor to create athree-dimensional color representation of the subject matter captured inthe images.

Alternatively, the described image-capture devices can be applied inconjunction with structured light, sonar (sound navigation and ranging),LiDAR (a portmanteau of “light” and “radar”), light-field cameratechnology, and other scanning methods to leverage camera projectionmapping to produce information models to support the creation of morerealistic virtual environments that adapt to changes in point of view,changes in position of a virtual or CG light source and for someenvironments changes in position of the sun. These other scanningmethodologies may supplant the role of a photogrammetry engine insolving for camera orientation, performing bundle adjustment, andsurface reconstruction in their respective ways.

The present image capture techniques can be adapted and applied toimages captured with conventional digital image sensors, binned sensors,multi-spectral sensors and even hyperspectral sensors, as may bedesired.

The present image-capture devices can be applied to collect images of anoutdoor location, an indoor location where ambient light is controllablydisabled, a location with restricted access, or even an underwater orsubterranean location. It can also be applied to collect images ofobjects that are either difficult or costly to transport to a studio,are sensitive archaeological artifacts, or pose any other type ofconstraint against movement within or from a present location. Any ofthe mentioned locations or objects may be captured in images using thedescribed image-capture devices. The captured images may be applied asinputs in image-processing techniques to generate a virtualrepresentation of a real-world scene or objects for use as an input toan editing tool. Such an editing tool can be used to modify a scene orused as props that may be integrated in a movie, television show orother cinematic production broadcast or distributed on a storage medium.These products may be stored and distributed in digital formats or viaother media such as film. In addition, any of the mentioned locationsmay be used to generate a virtual environment or object used in anexhibit, as a training aide, or in the development of a video game.

The various aspects will be described in detail with reference to theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.References made to particular examples and implementations are forillustrative purposes, and are not intended to limit the scope of theinventive systems as defined in the claims.

FIG. 1 is a schematic diagram illustrating the electromagnetic spectrum.The electromagnetic spectrum 10 includes the range of wavelengths orfrequencies over which electromagnetic radiation extends. Asillustrated, the electromagnetic spectrum 10 is commonly described bywavelength, a wave name, and/or frequency. The abscissa 11 includes ascale ranging from about 10 meters to about 10⁻¹⁴ meters. The abscissa11 depicts a decreasing wavelength from left to right across thediagram. Conversely, the abscissa 12 depicts an increasing frequencyfrom left to right across the diagram. The abscissa 12 includes a scaleranging from about 10⁸ to 10²² Hertz (Hz).

Moving from left to right across the electromagnetic spectrum 10 wavesnames include radio, microwave, infrared, ultraviolet, X-rays andGamma-rays. As indicated, by a corresponding horizontal two-headedarrow, each of the wave names corresponds to a range of theelectromagnetic spectrum 10 that corresponds to a range of wavelengthsand a range of frequencies. As also shown in FIG. 1 not all wave namescorrespond to a distinct and separate portion of the electromagneticspectrum 10. For example, microwaves overlap both radio waves andinfrared waves. By way of further example, X-ray waves or simply X-raysoverlap both ultraviolet waves and Gamma-ray waves or simply Gamma-rays.

Between the infrared and ultraviolet waves lies a range of theelectromagnetic spectrum 10 that includes visible light 13. Asillustrated, visible light 13 for a typical human observer ranges fromabout a wavelength of 780 nanometers (nm), which corresponds to thecolor red to a wavelength of about 390 nm, which corresponds to thecolor violet. These wavelengths correspond to a frequency band orfrequency range in the vicinity of about 430 THz (10¹² Hz) to 770 THz.Some human eye-brain systems may respond to electromagnetic waves below390 nm, while some other human eye-brain systems may not respond at allat those wavelengths. Similarly, some human eye-brain systems mayrespond to electromagnetic waves above 780 nm, while some other humaneye-brain systems may not respond at those wavelengths.

Technically, light does not have a color. Light is simply anelectromagnetic wave with a specific wavelength or a mixture ofwavelengths. An object that is emitting or reflecting light appears to ahuman to have a specific color as the result of the eye-brain responseto the wavelength or to a mixture of wavelengths. For example,electromagnetic waves with a wavelength of between about 580 to 595 nmappear yellow to most humans. In addition, a mixture of light thatappears green and light that appears red appears to be yellow to mosthumans. When electromagnetic waves having a broad range of wavelengthsbetween about 390 nm to 780 nm enter a human eye, most humans perceive“white” light.

Non-visible or invisible light corresponds to those portions of theelectromagnetic spectrum 10 outside of the range of visible light 13.More specifically, a first non-visible range includes electromagneticradiation with wavelengths longer than about 700 nm or frequencies ofless than about 430 THz. This first non-visible range includes, forexample, infrared, microwave and radio waves. A second non-visible rangeincludes electromagnetic radiation with wavelengths shorter than about390 nm or frequencies greater than about 770 THz. This secondnon-visible range includes, for example, ultraviolet, X-rays andGamma-rays.

FIG. 2 is a schematic diagram illustrating an exemplary real-world scene20 to be recorded with an image-capture device using novel image-capturetechniques. The example real-world scene 20 is a junction of two streetsin a city bordered by man-made structures such as two and three storybuildings. The various structures and features of the real-world scene20 can be defined in a three-dimensional coordinate system 30 orthree-dimensional space having an origin 31, an abscissa or X-axis 32,an ordinate or Y-axis 34, and a Z-axis 33.

In the illustrated embodiment, the three-dimensional coordinate system30 is a right-handed coordinate system. In a right-handed coordinatesystem the positive x and y axes point rightward and upward across thetwo-dimensional page and the negative z axis points forward or into thedepicted scene. Positive rotation is counterclockwise about the axis ofrotation.

It should be understood that alternative coordinate systems, such as aleft-handed coordinate system or a spherical-coordinate system (both notshown) may be used to develop a three-dimensional model of features in areal-world scene 20. While the origin 31 is not overlaid or associatedwith a physical feature in the illustrated real-world scene 20, such anassociation is convenient and may be preferred. For example, if asurveyor's pin or other boundary marker is available, the surveyor's pinor marker may be adopted as the origin 31 for the three-dimensionalvolume to be modeled.

Whatever coordinate system is used and whatever feature or features maybe used to define an origin, the process of developing the model of areal-world scene or location may benefit from a preliminary mapping of aspace to plan an effective strategy for positioning and collectingimages. Such a preliminary mapping may create a route or course thattraverses the three-dimensional volume. The route or course may includea flight plan to guide one or more aerial platforms to position animage-capture device as images are being exposed and stored. Such apreliminary investigation and plan may be used to define and extend thebounds of a known space into an unknown space, such as with a manned orunmanned original exploration of underwater features like a shipwreck orsubterranean features such as a cave.

As further illustrated by way of a relatively small insert near a lowerleftmost corner of a building that faces both streets, a material usedon the front of the building (e.g., concrete, granite, brick, etc.),which may include large enough surface variation to be measured by aphotogrammetry engine, is represented by a localized three-dimensionalpolygonal mesh 21. The polygonal mesh 21 is an arrangement of adjacentpolygons, the vertices of which are defined by a point cloud. In theillustrated embodiment, the point cloud is represented by vertices ofsome of the various polygons. Each of the vertices or points in thepoint cloud is identified by coordinates in a three-dimensionalcoordinate space or by a vector and a distance from a reference, suchas, origin 31, in a modeled volume. Since every point is identified bycoordinates in the three-dimensional coordinate space, each polygon orclosed area in the polygonal mesh 21 can be identified by its verticesor by a normal vector derived from the plane of the surface defined bythe vertices.

In the illustrated embodiment, a surface construction or reconstructionprocess has been performed. Such a surface reconstruction uses thelocations defined by the points of the point cloud to define athree-sided polygon or triangle. Alternative surface reconstructionalgorithms may use four points from the point cloud or other collectionsof points greater in number to represent surfaces of features in areal-world scene 20. However, surfaces represented by triangles andquadrilaterals are generally preferred. The closed areas of sub-portionsof a polygonal mesh 21 are often associated with a two-dimensionalunfolded version of the corresponding surface geometry. These twodimensional representations are commonly called UV maps. The letters “U”and “V” denote axes of a two-dimensional texture. When matched orprojected with appropriate color and relatively finer textureinformation in proper registration with the surface geometry over theentirety of the surfaces in the polygonal mesh 21 a three-dimensionalcolor model of the real-world scene 20 is created.

From the above it should be understood that photogrammetry techniquesare used to generate a model of the relatively large scale geometry thatphotogrammetry techniques can measure. That model is then used as aframework for locating and folding the color and relatively finervariations in surface textures as captured in two-dimensionalphotographs to generate a more realistic appearing three-dimensionalmodel of a real-world scene or location. This first improvedthree-dimensional color model is constructed solely from diffuse maps.

The same relatively large scale geometry is used to locate and unfold amodified two-dimensional image generated from an algorithmic combinationof color information from related photographs of nearly the same subjectmatter that includes a specular map isolated from the diffuse imagedataset. The addition of the isolated-specular surface texture as aseparate digital asset further improves the realistic response to CG orvirtual light in a virtual environment rendered from thethree-dimensional color model.

FIG. 3 is a schematic diagram illustrating an image-capture device 100within a portion of a real-world scene 300 including asubject-of-interest 310. In the illustrated example, the image-capturedevice 100 uses an alternative scanner to project an image frustum 320on the subject-of-interest 310. The image frustum 320 provides distance,orientation, and location information that can be used by an operator orphotographic processing systems in the image-capture device 100 toidentify the location in the real-world scene 300 where images are to becaptured. Although the subject matter captured in an image is describedabove as including a subject-of-interest 310 it should be understoodthat the image-capture device 100 is capable of recording images thatinclude a desired portion of a real-world scene 300 that may includemultiple surfaces of one or more objects present in a field of view whenthe image is exposed and temporarily stored in the image-capture device100.

The image-capture device 100 is arranged in a freestanding chassis orenclosure 102. In a first embodiment the freestanding chassis 102 a ismoved throughout the real-world scene 300 by an operator. In this firstembodiment, the freestanding chassis 102 a is representative of ahandheld mode of operation where device translation and rotation aredetermined for each exposure. Although the image-capture device 100 isdescribed above as being arranged within a freestanding chassis 102 a itshould be understood that the image-capture device 100 in someembodiments may be arranged with elements and control interfaces thatmay extend to or beyond the chassis. For example, one or more of abattery, an illumination source, a lens assembly, etc. may extend fromor be coupled to the freestanding chassis 102. When a separate batterypack is desired, one or more elements or subsystems of or the entireimage-capture device 100 may be connected by way of a cable or set ofwires to one or more batteries (not shown).

In an alternative embodiment, the freestanding chassis or enclosure 102b is coupled to an adjustable extension pole 340. A two section pole isillustrated. However, a pole with additional sections or pole segmentsthat connect to each other can be used. The extension pole 340 includesa section 342 a, a portion of which can be stored within a volumeenclosed within section 342 b and a portion of which can be extendedfrom section 342 b. An adjustment sleeve 345 uses friction forces alongthe longitudinal axis of the section 342 b and section 342 a totemporarily set the distance between an opposed or support end of thesection 342 b and the connection end of section 342 a connected to orplaced against a receiver portion along a surface of the freestandingchassis 102 b of the image-capture device 100. The adjustment sleeve 345can be manipulated (e.g., rotated) to reduce the radial forces beingapplied against the external surfaces of sections 342 a, 342 b when anoperator desires to adjust the length of the extension pole 340.

In operation, with a desired length temporarily set or fixed by theadjustment sleeve 345, the opposed or support end of the extension pole340 can be placed on the ground or another surface capable of supportingthe weight of the combination of the extension pole 340 and theimage-capture device 100 within the freestanding chassis 102 b. The pole340 can be held by an operator to prevent rotation. Alternatively, thepole 340 can be supported by a set of three or more guy wires (notshown).

In an alternative embodiment, the freestanding chassis or enclosure 102c is coupled to a vehicle 330. A drone is depicted schematically in anairborne mode of operation. A drone is one example of an airbornevehicle. Other airborne vehicles could be used to support thefreestanding chassis 102, as may be desired. In other embodiments, thevehicle 330 can be a land-based vehicle, a boat or other buoyant vehiclethat operates on or near the surface of a body of water, a submarinethat operates near or below a surface of a body of water, etc. One ormore such vehicles can be operated to assist in the relative positioningof the image-capture device 100 with respect to a subject-of-interest310 to be photographed.

In another alternative embodiment, the freestanding chassis or enclosure102 d is arranged with carriage supports 360 that hang below an elongateflexible member 350 between pole 340′ and pole 340″. In the illustratedarrangement, carriage support 360 a is connected near the upper leftwardfacing side of the freestanding chassis 102 d and carriage support 360 bis connected near the upper rightward facing side of the freestandingchassis 102 d. The elongate flexible member 350 passes through arespective opening in the carriage supports 360. The elongate flexiblemember 350 can be a wire, filament, rope, cable or cord that istemporarily connected at one or both of a first end 352 at pole 340′ andat a second end 354 at pole 340″. The respective lengths of the pole340′ and the pole 340″ can be adjusted to account for uneven terrain.

When so arranged, the freestanding chassis 102 d may be maneuveredlaterally with respect to a subject-of-interest 310 in a real-worldscene 300. Such maneuvering can be accomplished by applying an externalforce to the freestanding chassis 102 d with a hand, another pole, andor by attaching a string, rope, wire or cable to one of the carriagesupports 360 or to the freestanding chassis 102 d and pulling the sameto adjust the relative position of the freestanding chassis 102 dbetween the poles 340′, 340″. Alternatively, the carriage support 360 aand the carriage support 360 b may be suspended from a respective set ofrollers arranged to contact opposed portions along the surface of theelongate flexible member 350. One or both the respective sets of rollersmay be electromechanically driven by a remotely controlled system toposition the image-capture device 100 within the freestanding chassis102 d as may be desired between the pole 340′ and the pole 340″.

Whether the image-capture device 100 is handheld, connected to a pole orpoles, suspended from a lighter than air vehicle, suspended from a cablesupported between poles, suspended by wires or ropes from a man-made ornatural surface, or connected to a vehicle, an image sensor or imagesensors in the image-capture device 100 may not be stationary and insome modes of operation is necessarily non-stationary.

When the image-capture device 100 is handheld, an operator can adjustany function using interfaces and mechanisms for making suchadjustments. When the image-capture device 100 is connected to a pole340, suspended from a lighter than air vehicle, suspended via wires orropes from a man-made or natural surface, or connected to a floating orland-based vehicle, a wired or wireless interface may be used by anoperator to enter adjustments as may be desired as the image-capturedevice 100 is maneuvered about the real-world scene 300.

FIG. 4A is a schematic diagram of an embodiment of the image-capturedevice 100 of FIG. 3. As illustrated, the image-capture device 400 is anassembly of subsystems including an illumination source 410,illumination controller 420, an optional scanner subsystem 425, opticalsubsystem 430, shutter 440, processor 450 and memory 460. The processor450 is arranged to manage and coordinate the operation of the variousmechanical and electro-mechanical subsystems in the image-capture device400 and any peripheral systems, such as a battery or batteries, whichenergize the various components. The processor 450 can be enabled by a“system-on-chip” or SoC which includes a set of interconnectedelectronic circuits typically, but not exclusively, including a hardwarecore, a memory, and a communication interface. A hardware core mayinclude a variety of different types of processors, such as ageneral-purpose processor, a central processing unit (CPU), a digitalsignal processor (DSP), an auxiliary processor, a graphical processingunit, among other circuits. A hardware core may further embody otherhardware and hardware combinations, such as a field programmable gatearray (FPGA), an application-specific integrated circuit (ASIC), otherprogrammable logic device, discrete gate logic, transistor logic,performance monitoring hardware, etc.

The processor 450 may operate autonomously, in response to one or moreinputs received from an operator and or in conjunction with informationreceived from scanner subsystem 425. The scanner subsystem 425 mayinclude a remote sensing technology such as LiDAR which measuresdistance by illuminating a target with a laser and analyzing thereflected light. Such distance information can be applied by theprocessor 450 to set one or more operational parameters such as a focusadjustment, aperture, image sensor sensitivity, shutter speed. Inaddition, such distance information can be useful in guiding theposition of the image-capture device 400 as it traverses the real-worldscene 300.

Furthermore, the scanner subsystem 425 may be adapted to provide a pointcloud 21 and/or a polygonal mesh from the distance information which canbe stored in one or more data files in telemetry store 465.Alternatively or in addition to LiDAR, the scanner subsystem 425 mayinclude a system that projects a known pattern onto a subject or surfaceof interest and uses a mathematical reconstruction of any deformation inthe reflected pattern. When a subject having a surface-of-interest isobserved from multiple angles, the various reconstructions can be usedto identify common features to stitch scanned portions of a scenetogether or to maneuver the image-capture device 400 along apredetermined course or path through a previously scanned location ofinterest.

However embodied, the processor 450 is arranged to generate andcommunicate a control signal or set of control signals at appropriatetimes to the illumination controller 420. In turn, the illuminationcontroller 420 enables the emitter 416 which generates and emitscontrolled light in a direction substantially orthogonal to an externalor mounting face of the image capture device 400. Controlled light ispolarized in one or more desired polarization angles.

As illustrated schematically in FIG. 7A and in FIG. 7B, a polarizer orpolarizing filter 710, 715 substantially reduces the passage ofelectromagnetic radiation or light 700 in other than a desired plane.Light 700 is shown as a pair of two-headed arrows 702, 704 thatrepresent respective traveling waves that oscillate about theirintersection at point 705. In the illustrated arrangement, light 700 (orthe traveling wave) is traveling into or out from the page at theintersection 705 of arrow 702 and arrow 704. Schematically, the “+” signrepresents an arrangement of the polarizing filter 710 in registrationwith the intersection 705 of the two-headed arrows 702, 704. That is,the polarizing filter 710 may be placed in front of a light beam 700 orray traveling in a direction out of the page or towards an observer.When so arranged, the polarizing filter 710 prevents the passage oflight 700 oscillating in any other orientation than vertical (up anddown the page) beyond the polarizing filter 710. Stated another way,polarizing filter 710 allows polarized light 720, which is oscillatingvertically or along a plane identified schematically as being parallelwith a line defined by 90° and 270° labels along a unit circle 722.

Similarly, in FIG. 7B, light 700 is polarized by placing a polarizingfilter 715 that is arranged to allow passage of light 700 oscillatinghorizontally in registration with the light 700. That is, the polarizingfilter 715 may be placed in front of a light beam 700 or ray travelingin a direction out of the page or towards an observer. When so arranged,the polarizing filter 715 prevents the passage of light 700 oscillatingin any other orientation than horizontal (left and right across thepage) beyond the polarizing filter 715. Stated another way, polarizingfilter 715 allows polarized light 725, which is oscillating horizontallyor along a plane identified schematically as being parallel with a linedefined by the 0° and 180° labels along a unit circle 727. When deployedas depicted in FIG. 7A and FIG. 7B, the polarizing filter 710 allowspolarized light 720 oscillating in a first orientation or plane to passand polarizing filter 715 allows polarized light oscillating in a secondorientation or plane orthogonal with respect to the first orientation topass.

In the embodiment illustrated in FIG. 4A, the emitter 416 is a compositeelement that includes a first emitter 412, which generates and directsnon-polarized light through a polarizer 415 a and further includes asecond emitter 414, which generates and directs non-polarized lightthrough a polarizer 415 b. The polarizer 415 a and the polarizer 415 band at least a portion of the first emitter 412 and the second emitter414 are separated by an opaque barrier 411 that prevents light from thefirst emitter 412 from passing through the polarizer 415 b and similarlyprevents light from the second emitter 414 from passing through thepolarizer 415 a. Polarized light 413, or light that passes beyond thepolarizer 415 a that is oscillating in a first orientation, is directedaway from the image-capture device 400 toward a surface-of-interest 310in a real-world scene 300. Similarly, polarized light 417 that passesbeyond the polarizer 415 b that is oscillating in a second orientationis directed away from the image-capture device 400 toward asurface-of-interest 310 in a real-world scene 300. The polarizer 415 aand the polarizer 415 b are arranged so that the polarized light 413 andthe polarized light 417 are substantially orthogonal with respect to theother. The polarized light 413 and the polarized light 417 are reflectedby the subject-of-interest 310. In addition, an opaque barrier 431prevents the polarized light 413 and the polarized light 417 fromentering the optical subsystem 430 without reflecting from a surface orobject of interest. As indicated schematically in FIG. 4A, reflectedlight 419 from the surface-of-interest 310 and responsive to theincident polarized light 413 and incident polarized light 417 isreceived by the optical subsystem 430.

The optical subsystem 430 includes a polarizer 432, lens housing 433 andaperture 434. The aperture 434 is a diaphragm that controls the size ofan opening that permits the reflected and polarized light to passthrough the shutter 440 on its way to the image sensor 445. A lens (notshown) within the lens housing 433 focuses the reflected light 419 atthe image sensor 445. The polarizer 432 reduces the amount of lightincident upon the lens housing 433 by permitting light having a specificpolarization state or oscillating orientation to pass through andsubstantially reducing reflected light 419 present at a surface of thepolarizer 432 having polarization states other than the specificpolarization state. When the polarizer 432 is arranged to allow lightoscillating in an orientation that is within a few degrees of anorientation defined by one of the polarizer 415 a or the polarizer 415 b(when the polarizer 415 a has an orientation that is approximatelyorthogonal or shifted 90° to the orientation of the polarizer 415 b) andwhen both the emitter 412 and the emitter 414 are energized together,and the shutter 440 is opened, the sensor 445 is exposed to co-polarizedlight 441 and cross-polarized light 442. Alternatively, when theillumination controller 420 directs the illumination source to energizeone of the emitter 412 or the emitter 414, and when the shutter 440 isopened, the sensor 445 is exposed to either co-polarized light 441 aloneor cross-polarized light alone 442.

When the image sensor 445 is sensitive to visible light, the imagesensor 445 generates electrical signals corresponding to the amount ofelectromagnetic radiation in each of the red, green, and blue frequencyranges. The electrical signals are composited and stored in a uniformmanner in memory 460 as an image 462 a. The shutter 440 and aperture 434are opened and closed as directed by control signals generated in andcommunicated from the processor 450. These control signals arecoordinated with the signal or signals communicated to the illuminationcontroller 420 to ensure that the subject-of-interest 310 issufficiently illuminated and a suitable image is captured and stored inthe memory 460. In close proximity to this first exposure and capture ofthe image 462 a, the processor 450 generates a signal or signals thatdirect the illumination controller 420 to enable the other of theemitter 412 or the emitter 414.

The polarizers 415 a, 415 b may be linear polarizers embodied in a film.Alternatively, polarization may be controlled in specially constructedlight emitting diodes. Alternatively, one or both polarizers 415 a, 415b can be embodied with a set of laminated plates. The plates includeglass substrates with electrodes, and a nematic liquid crystal layerbetween the electrode layers. Appropriately energizing the electrodelayers at a desired time instantly switches the state of the polarizingangle from a first orientation angle of 0° to a second orientation angleof 90°.

When a single electronically enabled polarizer 415 is included in theimage-capture device 400, the emitter 412 and the emitter 414 may becoupled to optimize total light output. In such an arrangement, theillumination power may be controlled by adjusting a bias current that iscoupled to the individual light emitting elements (e.g., light-emittingdiodes) forming a composite emitter 416. When the polarizer 415 isenabled the bias current is controllably adjusted between exposures tocompensate for the varying light loss associated with co- andcross-polarized exposures.

As described, when a polarizer is configured to transmit light wavesrunning in parallel to those allowed to pass through a second polarizercovering a lens, the first polarizer placed between an illuminationsource and a subject-of-interest, a relatively lower illumination powermay be required to illuminate the subject-of-interest during one of thepaired or related image exposures. When a polarizer 415 is eitherpermanently introduced in the case of a film or temporarily enabled whenan electronically controlled polarizer is placed between an illuminationsource 410 and a subject-of-interest, a relatively larger illuminationpower is provided to illuminate the subject-of-interest (e.g., a surfaceor surfaces) during the remaining one of the paired image exposures. Theelapsed time between a first exposure and a subsequent exposure iscontrolled by the processor 450 by synchronizing the aperture 434,shutter 440 and the illumination controller 420.

Accordingly, polarized light 413 in a first orientation or polarizedlight 417 in a second orientation is directed away from theimage-capture device 400 toward a subject-of-interest 310 in areal-world scene 300. Reflected light 419 from the subject-of-interest310 is received by the optical subsystem 430. The optical subsystem 430and shutter 440 are controllably enabled in a coordinated manner withthe control signal or signals communicated to the illuminationcontroller 420 to open the aperture 434 and shutter 440 to capture image462 b.

When a polarizing filter is located between the subject-of-interest andan image sensor, the angle of polarization relative to a given lightsource and reflected off subject matter with a given reflectanceproperty, may reduce the amount of light passed through to the imagesensor anywhere between 1.5 f-stops for co-polarized exposures toupwards of 4 f-stops for cross-polarized exposures. Auto-exposurecameras will adjust for the loss of available light by widening theaperture, lengthening the time the shutter is open, and/or increasingthe sensitivity of the image sensor. However, metering and auto-focussensors in certain cameras, including virtually all auto-focus SLRs,will not work properly with linear polarizers because the beamsplittersused to split off the light for focusing and metering are polarizationdependent. In addition, linearly-polarized light may also defeat theaction of the anti-aliasing filter (i.e., a low-pass filter) on theimaging sensor. Accordingly, auto-focus SLRs will often use a circularpolarizer. A circular polarizer consists of a linear polarizer on thefront, with a quarter-wave plate on the back. The quarter-wave plateconverts the selected polarization to circularly polarized light insidethe image-capture system. These circular polarizers work with all typesof cameras, because mirrors and beamsplitters split circularly polarizedlight the same way they split non-polarized light.

A linear polarizing filter can be easily distinguished from a circularpolarizing filter. In linear polarizing filters, the polarizing effectworks regardless of which side of the filter the scene is viewed from.In contrast, with “circular” polarizing filters, the polarizing effectworks when the scene is viewed from one side of the filter, but does notwork when looking through the opposed side of the filter. It is notedthat linear polarizers deliver a truer specular reflectance model thando circular polarizers.

The principles involved with capturing two images in quick successionwith different states of polarization defined by the relative rotationof separate polarizing filters with a first polarizing filter 415 a, 415b proximal to the illumination source and a second polarizing filter 432between the subject of interest and an image sensor 445 and withdifferent illumination power levels can be applied to any lightsource/fixture and many photographic system architectures. Independentof the type of light source deployed in an emitter 416, theimage-capture device 400 optimizes light output where light is needed toreduce or eliminate shadows and to provide sufficient reflected light419 across the entire two-dimensional array of photosensitive electronicelements in the image sensor 445. For example, light rays castsubstantially proximal to and on-axis with respect to the longitudinalaxis 470 of the lens 430, limited only by the ability to place lightgenerating fixtures as close to the outer edge of a lens assembly asimposed by the physical tolerances of manufacturing, can be used toreduce and in some situations all but eliminate shadows. To achievenearly uniform illumination across the surface-of-interest the lightdirected away from the image-capture device 400 by the emitter 412, theemitter 414, or a combination emitter 416 and/or the individual elementscomprising the described emitters may be collimated. In addition tocollimating the light, the individual elements comprising the emitters412, 414, 416 may be selected for their ability to produce a uniformoutput over a desired range of frequencies in response to a desiredinput.

In terms of the volume of light output by the emitter 412 and theemitter 414, light output is paramount to compensate for light loss dueto the polarizer(s) 415, 432 as photogrammetry is dependent onlow-noise, adequately exposed and focused surface textures. Each ofthese objectives are compromised by conventional solutions with 1)slower shutter speeds, which introduce the problem of inadequatetemporal resolution, 2) wider apertures, which predict shallower depthof field, which in effect compromises the need for in-focus pixels, and3) higher imager sensitivity, which causes “noise” or larger grain inthe images, which both frustrates the photogrammetry engine's abilitiesto identify common points of interest between overlapping photos, aswell as compromises the quality of the texture maps used to skin thegeometry returned from the photogrammetry.

Accordingly, in support of optimizing light output, attention may bedirected to minimizing the space between light emitting elements in theemitter 412, the emitter 414 or the composite emitter 416 and the outersurface of the lens assembly 433, thereby fitting a greater number oflight emitting elements into that space.

Light that is directed from the image-capture device 400 toward asubject or surface to be captured in an image or exposure (bothcross-polarized light 413 and co-polarized light 417) preferablyincludes a range of visible wavelengths. The illustrated embodimentshows co-polarized or polarized light 417 being emitted or directed awayfrom the image-capture device 400 relatively further away from theoptical subsystem 430 than the non-polarized light 413 that emanatesfrom the image-capture device 400. However, the image-capture system 400is not so limited. In some embodiments, both the emitter 412 and theemitter 414 include respective sets of light-emitting diodes orflashtubes that are arranged about the perimeter of the opticalsubsystem 430. In these embodiments, the individual elements forming theseparately controlled emitters 412, 414 may be alternated element byelement, row by row, or arranged in other periodic arrangements aboutthe optical subsystem 430 and more specifically the outer surface of alens housing (not shown).

In addition to being separately energized by the illumination controller420, the individual elements of the emitter 412 and the emitter 414 mayalso be separately energized to finely adjust the luminous flux that isprojected from the image-capture device 400 to illuminate thesubject-of-interest.

As further indicated in FIG. 4A, the image sensor 445 may comprise anarray of elements sensitive to visible light, non-visible light (one orboth of ultraviolet and infrared light), multi-spectral light and orhyper-spectral light. Although conventional image sensors may includeelements sensitive to one or the other of visible light and non-visiblelight, the described imaging techniques can be used with image sensorsthat may combine various ranges of electromagnetic radiationsensitivity. For example, these imaging techniques can be applied to animage sensor that combines infrared sensitive elements with visiblelight sensitive elements. In other example embodiments, the image sensor445 may be responsive to multi-spectral light outside of the range ofvisible light. When the image sensor 445 is sensitive to a combinationof various ranges of electromagnetic radiation, the separate elementsforming the emitter 412, the emitter 414, or a composite emitter 416 maybe arranged with elements capable of producing one or more ofnon-visible light, multi-spectral light and or hyper-spectral light.

However arranged with respect to the range or ranges of sensitivity toelectromagnetic radiation, the image sensor 445 of the image-capturedevice 400 will benefit from one or more stabilization systems. Forexample, the Sony Corporation has developed a full-frame camera with5-axis image stabilization. When energized, the stabilization systemuses suitably positioned magnets and actuators to controllably float theimage sensor within the camera body. When a subject-of-interest is infocus and the lens assembly communicates the focal length to thestabilization system controller, pitch (rotation about the x-axis), yaw(rotation about the Y-axis, relative shift along the X-axis or Y-axisand rotation about the longitudinal axis of the lens assembly in the X-Yplane can be countered to produce an exposure with substantially reducedimage blur even in low-light conditions, while at the same timeprotecting against a change in camera orientation between exposures ofimage pairs, thus ensuring nearly identical rasters as required forisolating specular data using the difference blend between each layeredimage pair. Such image sensor stabilization techniques provide greaterlatitude to an operator when selecting an aperture setting.

The first image 462 a and the second image 462 b can be temporarilystored in the image-capture device 400 such as in memory 460 for latertransfer to an image-processing system. Such a transfer need not bedirect as image files can be stored on a data-storage medium, onnetwork-coupled storage devices, or on both for later transfer to animage-processing system. In addition, such image information transferscan occur in alternative sequence and even substantially together oroverlapping in time. Furthermore, corresponding portions of each of theimages may be processed before the entirety of a raster 463 or array ofpixels comprising an entire image is received by the image-processingsystem. Corresponding portions of each of the images are defined both byrelative location in an array of pixels and the corresponding datavalues associated with the sensor at those pixel element locations. Forexample, if the image sensor is a sensor that is responsive to portionsof the electromagnetic spectrum perceived by the average human tocorrespond to the color red, green and blue, a red data value from afirst pixel location defined by a row and a column position with respectto an origin of the raster of pixel elements in the image sensor ismathematically combined (e.g., through subtraction) with a correspondingdata value from the same relative pixel location from the remainingimage. Similarly, a green data value and a blue data value from thefirst pixel location, respectively, are mathematically combined withcorresponding data values from the same relative pixel location from theremaining image.

When a binned image sensor is used to capture the image information, twoor more adjacent pixels of a similar sensitivity range are sampledtogether to produce a data value. For example, an integer number of“red” wavelength photosensitive elements are sampled together to producea single data value representative of these wavelengths present in anarea of the image sensor. This same sampling technique can be applied to“green” wavelength photosensitive elements, “blue” wavelengthphotosensitive elements as well as other frequency ranges of theelectromagnetic spectrum and the opacity channel as may be desired.

Image data can be arranged in any order using any desired number of bitsto represent data values corresponding to the electrical signal producedat a corresponding location in the image sensor at a defined location inthe raster of pixels. In computer graphics, pixels encoding the RGBAcolor space information, where the channel defined by the letter Acorresponds to opacity, are stored in computer memory or in files ondisk, in well-defined formats. In a common format the intensity of eachchannel sampled by the image sensor is defined by 8 bits, and arearranged in memory in such a manner that a single 32-bit unsignedinteger has the alpha or “A” sample in the highest 8 bits, followed bythe red sample, green sample and the blue sample in the lowest 8 bits.This is often called “ARGB.” Other standards including different numbersof bits in other sequences are known and used in storing RGB and Achannel information. Still other data storage arrangements will be usedin conjunction with reflected light captured by a multi-spectral imagesensor and a hyper-spectral image sensor.

As further indicated in FIG. 4A, a telemetry store 465 may includedevice info including image capture device parameters, as well as deviceorientation and location information in a three-dimensional volume. Thetelemetry store 465 will include such data for each instance of an image462 a through 462 n. Information in the telemetry store 465 will betransferred with the images 462 to an image processing system (notshown).

The schematic diagram in FIG. 4B includes an arrangement of theimage-capture device 400 including a composite emitter 416 thatsurrounds the lens assembly 433 such that the likelihood of shadows issubstantially reduced, or for some surfaces and separation distancesbetween the image-capture device 400 and the subject-of-interest,shadows are entirely avoided. As shown, the image sensor 445 and lensassembly 433 are arranged about a longitudinal axis or centerline 447.The longitudinal axis 447 extends in the direction of a normal vectorfrom the photosensitive elements in the image sensor 445 and through thecenter of lens assembly 433. In the illustrated arrangement, the emitter416 is shown in a partial section (as if the separately controlledemitter 412 and emitter 414 were cut along a plane that passes throughcenterline or longitudinal 447). When the lens assembly 433 is shapedlike a cylinder, the set of light-emitting diodes or flashtubes formingthe emitter 412 and/or the emitter 414 can be arranged in an arc,semicircle or an annular ring so that the light emitting elements can bearranged adjacent to or nearly against the outer surface of the lensassembly 433.

Although the polarizer 415 a and the polarizer 415 b are adjacent to theemitter 412 and the emitter 414 in the illustrated arrangement to ensurea first orientation of emitted light and a second orientation of emittedlight are substantially orthogonal to one another, the image capturedevice 400 is not necessarily so limited. For example, in an alternativeembodiment (not shown) the separate light emitting elements that formthe emitter 412 and the emitter 414 are arranged with a collimatingdome, lens or other structure arranged to emit light in a desiredpolarization or orientation. A first orientation or plane correspondingto the emitter 412 is orthogonal to a second orientation or planecorresponding to the emitter 414. As shown in the embodimentsillustrated in FIG. 4A and FIG. 4C, a circular polarizer 432 may bearranged in or on the lens housing 433 to capture corresponding imagesof the same subject-of-interest with co-polarized reflected light andcross-polarized reflected light.

When the emitter 416 is arranged in the shape of a ring (or rings) thatsurrounds the lens assembly 433, a distance, d, defines the spacebetween the outer surface of the lens assembly 433 and the innerdiameter of the emitter 416. A separate distance D₁ is the distance fromthe center of the image sensor 445 (or lens assembly 433) to the innerdiameter of the emitter 416. A third distance D_(SS) is the distancebetween the surface of the image sensor 445 and the surface-of-interestalong the camera orientation or the longitudinal axis 447 of the lenshousing 433. A fourth distance d_(offset) is the distance between theforward most surface of a substrate 472 or circuit board that supportsand distributes the necessary signals to controllably energizeindividual light-emitting diodes or flashtubes of the emitter 412 and arespective substrate 474 or circuit board associated with emitter 414.This fourth distance is selected in accordance with the physicaldimension of the corresponding elements forming the emitter 412 and theemitter 414 in the direction of the longitudinal axis 447 of the lenshousing 433 so that a forward most or emitting surface of the respectivedevices is aligned or is very close to being aligned with the forwardmost surface of the lens housing 433 so as to reduce the possibility ofor even avoid entirely casting a shadow on the surface of interest.

As indicated by a single arrow, polarized light 413 or polarized light417 is directed away from the emitter 416 of the image-capture device400 toward the surface-of-interest or subject-of-interest where thereflected light 419 is redirected by an angle, σ, along a vector that issubstantially on-axis with the centerline or longitudinal axis 447 ofthe lens housing 433. In an example embodiment, where the lens assembly433 has an outer diameter of approximately 87 mm, the distance d isabout 1 mm and the image-capture device 400 is about 1 m from thesurface-of-interest, the angle σ is approximately 2.5°. The distancebetween the longitudinal axis 447 and the inner diameter of the emitter416 can be used in Equation 1 to solve for the angle θ.

$\begin{matrix}{\sigma^{o} = {\tan^{- 1}\frac{D_{1}}{D_{SS}}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

When the angle σ is less than about 10° for separation distances ofabout 1 m or greater, shadows are substantially and significantlyreduced in images that include most surfaces-of-interest. When the angleσ is less than about 5° for separation distances of about 1 m orgreater, shadows are more significantly reduced in images that includeeven more surfaces-of-interest in real-world environments. When theangle σ is less than or about 2.5° for separation distances of about 1 mor greater, shadows are avoided in images for nearly all surfaces in areal-world scene. Consequently, images or surface textures includingsubject matter illuminated in such a manner, that is when the angle σ isless than about 10° for separation distances of about 1 m or greater aresubstantially shadow free. Thus, the illumination source 410 of theimage-capture device 400 illuminates one or more surfaces in a locationsuch that reflected light from the one or more surfaces is substantiallyshadow free.

FIG. 4C is a schematic diagram of an alternative embodiment of theimage-capture device of FIG. 3. A substrate or mount 491 is arrangedabout the lens housing 433 on a surface 486 of the camera enclosure 485.The mount 491 is arranged to ensure that the emitting surface or forwardmost facing surface of the polarizer 415 is closely aligned with theforward most facing surface of the polarizer 432 arranged on the lenshousing 433.

In the illustrated arrangement, the illumination controller 420 and acorresponding power source 490 are outside of a camera enclosure 485. Asillustrated, the power source 490 is coupled to the illuminationcontroller via conductors arranged in a flexible connection 481. Thepower supply 490 may be arranged with one or more circuits (not shown)configured to monitor one or more conditions of storage cells in thepower supply 490. Similarly, the illumination controller 420 may bearranged with one or more circuits (not shown) for monitoring operatingconditions of the drive and or bias current generating circuits in theillumination controller 420.

The illumination controller 420 operates in response to asynchronization signal generated within the camera enclosure 485 andprovided on connection 488. In turn, the illumination controller 420generates various signals communicated along connection 482 to theemitter 412 and along connection 483 to the emitter 414 such as abiasing current that controllably enables and varies the illuminationoutput from the emitter 412 and the emitter 414 at desired times. Inaddition, the illumination controller 420 generates various signalscommunicated along connection 484 to one or both of the polarizer 415 aand/or the polarizer 415 b to controllably adjust the orientation angleof light permitted to pass through the respective polarizer 415 a, 415b.

The camera enclosure 485 supports an optical subsystem 430, a shutter440 and an image sensor 445 as well as a corresponding processor 450,memory 460 and an optional scanner subsystem 425. As described inassociation with the embodiment illustrated in FIG. 4A, these elementsenable the image capture device 400′ to capture and temporarily store anumber of desired images of a subject-of-interest 310 and theimage-capture device is controllably positioned in a real-world scene300.

As further indicated in FIG. 4C polarized light 417 is generated by theemitter 412 and/or emitter 414 where the generated light is filtered bya corresponding polarizer 415 a, 415 b to generate polarized light 417having either a first orientation 457 or a second orientation 458. Thepolarized light 417 is collimated such that the polarized light 417 isaligned and directed away from the image-capture device 400′ in adirection that is substantially parallel to a longitudinal axis 470 ofthe optical subsystem 470. An opaque barrier 411 interposed between thepolarizer 415 a and the polarizer 415 b as well as the emitter 412 andthe emitter 414 prevents light generated by emitter 412 from passingthrough the polarizer 415 b and further prevents light generated by theemitter 414 from passing through the polarizer 415 a. After encounteringthe various surfaces of a subject-of-interest 310 the incident polarizedlight 417 becomes reflected light 419 having either a first orientation457 r or a second orientation 458 r. When the polarizer 432 issubstantially aligned with one of the first orientation 457 r or thesecond orientation 458 r the image capture device 400′ captures andtemporarily stores images that were the result of co-polarized light andcross-polarized light of substantially the same subject-of-interest 310in a real world scene 300. As further illustrated in FIG. 4C, a barrier431 prevents light passing through the polarizer 415 a or light passingthrough the emitter 415 b from entering the optical subsystem 430without first reflecting from a surface or surfaces of thesubject-of-interest 310.

FIG. 4D illustrates another alternative embodiment of the image-capturedevice of FIG. 3. Here, an emitter 416 is arranged on the mount 491 andunder a single polarizer 415. An opaque barrier 431 prevents lightgenerated by the emitter 416 from entering the optical subsystem 430without being reflected from a surface or surfaces of thesubject-of-interest 310.

FIG. 5 is a schematic diagram of an alternative embodiment of theimage-capture device of FIG. 3. As illustrated, the image-capture device500 is an assembly of subsystems including an illumination source 512,illumination controller 520, optical subsystem 530, processor 450 andmemory 460. A device enclosure 531 supports a lens housing 533 andprotects the processor 450 memory 460 and internal components of opticalsubsystem 530. As shown by broken imaginary lines A-A, the illuminationsource 512 is arranged as an annularly shaped ring of light-emittingsemiconductors 532 that closely abuts the outermost surface of the lenshousing 533. A polarizer 515 is similarly shaped and arranged inregistration above the illumination source 512. The light emittingsemiconductors 532 may be arranged with a collimating dome or lens thataligns the emitted light so that light generated by the light-emittingdevices is transmitted in a direction that is substantially parallel toa longitudinal axis of the lens assembly 533. The polarizer 515, whichmay be a layer of polarizing film, filters the collimated light so thatlight that passes beyond the polarizer 515 oscillates in a firstorientation about a ray in a direction substantially parallel to alongitudinal axis of the lens housing 533.

The processor 450 is arranged to manage and coordinate the operation ofthe various mechanical and electro-mechanical subsystems in theimage-capture device 500. A circuit or circuits provided in theillumination controller 520 and/or in conjunction with an assembly ofrechargeable cells or battery pack may be used to monitor one or moreparameters of the rechargeable cells (not shown) used to controllablyenergize light-emitting semiconductors 532 arranged about theillumination source 512. The processor 450 may operate autonomously, inresponse to one or more inputs received from an operator and or inconjunction with information received from an optional scanner subsystem425 (not shown). The scanner subsystem 425 may include a remote sensingtechnology such as LiDAR which measures distance by illuminating atarget with a laser and analyzing the reflected light. Such distanceinformation can be applied by the processor 450 to set one or moreoperational parameters such as a focus adjustment, aperture, imagesensor sensitivity, shutter speed. In addition, such distanceinformation can be useful in guiding the position of the image-capturedevice 500 as it traverses the real-world scene 300. The processor 450generates a synchronization signal which is communicated alongconnection 540 to the illumination controller 520. The illuminationcontroller 520 includes one or more bias current generation circuits,the outputs of which are communicated along connection 541 tocontrollably energize the illumination source 512.

The collimated and polarized light directed away from the enclosure 531returns in the form of reflected light 419 that is focused by lens 511in the direction of a beamsplitter 522. The beamsplitter 522 permits aportion of the incident reflected light 419 to pass through to a firstoptical path 521 that intersects a polarizer 524 and an image sensor525. A second portion of the incident reflected light 419 is reflectedby a surface of the beamsplitter 522 to a second optical path 527 thatintersects a polarizer 528 and image sensor 529. A single shutter (notshown) may be provided in a transverse orientation to the reflectedlight 419 prior to the beamsplitter 522. Alternatively, separateshutters (not shown) may be arranged after the polarizers 524, 528 inthe respective optical paths. The processor 450 controls the variouselectromechanical elements to coordinate the capture and temporarystorage in the memory 460 of image pairs 462 a through 462 n of asubject-of-interest in a real world scene. When one of the polarizer 524and the polarizer 528 is in the same orientation as the polarizer 515and the remaining one of the polarizer 524 and the polarizer 528 isarranged orthogonally with respect to the first orientation, one of theimages in an image pair is responsive to co-polarized light while theother image in the image pair is responsive to cross-polarized light.

As further indicated by way of dashed lines the memory 460 may bearranged to store various information in image store 550 to enable apost capture image processing of the image pairs 462 a through 462 n asmay be desired. In this regard, the image store 550 may include deviceinformation 555 such as the various adjustable parameters that were setwhen a particular image pair instance was captured. In addition, theimage store 550 may include location and orientation information thatidentifies both the position and rotation of the image capture device500 in the real world scene. This information may be recorded inconjunction with time information 567 with respect to an identifiedorigin in a three-dimensional image space to serve as a reference forsequencing and or stitching the image information in a model of a realworld scene.

FIG. 6 is a schematic diagram of another example embodiment of theimage-capture device of FIG. 3. The image-capture device 600 is arrangedas a planar array of devices distributed across a mounting surface 610of a substrate or circuit board supported by a enclosure or otherstructural elements (not shown) as may be desired. Electricallycontrolled devices distributed across the mounting surface 610 includeemitters 611 and a host of image sensors 612, image sensors 613, andimage sensors 614.

As indicated in the illustrated embodiment, the emitters 611 may bealigned in arrangement with a polarizing film or other light polarizingelement to filter light oscillating in all but a desired orientationthat is directed in a direction substantially orthogonal to the plane ofthe mounting surface 611. The image sensors 612 are arranged with apolarizing filter that is substantially aligned with the desiredorientation of the light generated by and directed away from theimage-capture device 600 by the emitters 611. The image sensors 613 arearranged with a polarizing filter that is substantially orthogonal to orshifted by 90° from the desired orientation of the light directed awayfrom the image-capture device 600 by the emitters 611 and orthogonal tothe polarizing filter associated with each of the image sensors 612. Theimage sensors 614 are arranged without a polarizing filter and areavailable to capture reflected light oscillating in any and allorientations. Consequently, as more image sensors 614 are energized, asignal to noise ratio in the image information provided by the imagesensors 612, image sensors 613 and image sensors 614 can be expected toincrease.

Light that is generated within the separate emitters 611 is polarizedand directed away from the mounting surface 610 and returns to thedistributed image sensors 612, image sensors 613 and image sensors 614after having been reflected by a subject or subjects of interest withinthe field of view of the image-capture device 600. The arrangement ofthe polarizing films or other structures in registration with the imagesensors 612 and the image sensors 613 where the respective orientationsof light that passes through the polarizer is orthogonal enables theimage-capture device 600 to generate images responsive to co-polarizedlight and cross-polarized light, respectively, with reflected light fromthe same subject matter.

As further illustrated in FIG. 6, a separation distance between adjacentemitters 611 arranged along the mounting surface 610 is dependent upon aminimum manufacturing tolerance when the mounting surface 610 is asurface of a printed circuit board and the emitters 611 are formed fromsemiconductor devices. Although each emitter 611 is depicted as acircular shaped singular element generally arranged in a set of closelypositioned emitters 611 in a diamond-like shape across the mountingsurface 610, it should be understood that other arrangements are bothpossible and contemplated. For example, depending on the relative sizesof the areas of the separate image sensors 612, 613, 614 and the areasof the individual semiconductor(s), a square shaped arrangement ofemitters 611 in alignment with the edges of one or more of the imagesensors 612, 613, 614 are possible and may permit more emitting devicesto be placed adjacent to a respective perimeter of one or more selectimage sensor 612, 613, 614. While the illustrated embodiment includesrelated emitters 611 that do not surround image sensors interspersedbetween columns of image sensors of alternating image sensors 612, 613,614, it should be understood that a host of alternative arrangements maybe deployed to achieve any number of efficiencies in density of selectsemiconductor devices across the mounting surface 610 or to achieveother desired effects in the image information. Although the illustratedarrangement shows a single emitter 611 arranged as a circle, it shouldbe understood that light may be generated by sets of semiconductordevices that were produced on a single die. Such dies may be singulated,sawed or cut in any number of various arrangements with a desired numberof light-emitting semiconductor devices arranged thereon.

It should be noted that the term “comprising” does not exclude otherelements or features and the terms “a” or “an” do not exclude aplurality. Also elements described in association with differentembodiments may be combined.

One or more illustrative or exemplary embodiments of the invention havebeen described above. However, it is to be understood that the improvedimage-capture devices are defined by the appended claims and are notlimited to the specific embodiments described.

List of Reference Symbols in the Drawings  10 electromagnetic spectrum 11, 12 abscissa  13 visible light  20, 300 real-world scene  21polygonal mesh  30 coordinate system  31 origin  32 x-axis  33 z-axis 34 y-axis 100, 400, 500 image-capture device 102 enclosure 310subject-of-interest 320 frustum 330 vehicle 340, 340′, 340″ pole 342section 345 adjustment sleeve 350 elongate flexible member 352 end 354end 360 carriage support 410 illumination source 411 barrier 412, 414,416 emitter 413 polarized light 415 polarizer 417 polarized light 419reflected light 420, 520 illumination controller 425 scanner subsystem430, 530 optical subsystem 431 barrier 432 polarizer 433, 533 lenshousing 434 aperture 440 shutter 441 co-polarized light 442cross-polarized light 445 sensor 450 processor 460 memory 462 imageinstance 463 raster 465 telemetry store d distance d_(offset) offset D₁distance D_(ss) distance σ angle of incidence 470 longitudinal axis 472substrate 474 substrate 481 connection 482 connection 483 connection 484connection 485 enclosure 486 mounting surface 488 connection 490 powersupply 491 mount 497 polarized light (1^(st) orientation) 497r reflectedlight 498 polarized light (2^(nd) orientation) 498r reflected light 510device enclosure 511 lens 512 illumination source 515 polarizer 521optical path 522 beamsplitter 523 light 524 polarizer 525 image sensor527 twice reflected light 528 polarizer 529 image sensor 531 mountingsurface 532 semiconductors 540 connection 550 image store 555 deviceinformation 556 raster 567 time 600 device enclosure 610 mountingsurface 611 emitters 612 image sensors 613 image sensors 614 imagesensors 700 light 702 two-headed arrow 704 two-headed arrow 705intersection 710 polarizing film 715 polarizing film 720 polarized light722 unit circle 725 polarized light 727 unit circle

I claim:
 1. An image-capture device, comprising: an enclosure; a lensarranged in a lens housing supported by the enclosure; an illuminationsource having separately energized light emitters surrounding aperimeter of the lens housing, wherein when a first light emitter isenergized the image-capture device directs light oscillating in a firstorientation away from the image-capture device and wherein when a secondlight emitter is energized, the image-capture device directs lightoscillating in a second orientation different from the first orientationaway from the image-capture device, wherein one of the first lightemitter and the second light emitter are formed from a ring of elementsconcentrically arranged about the lens housing, wherein one of the firstlight emitter and the second light emitter include elements arranged inmore than one ring surrounding the lens, wherein a first substrate uponwhich elements in a first ring are arranged is offset from a secondsubstrate upon which elements in a concentric ring arranged about thefirst ring are located, wherein a depth of the offset keeps a respectiveemitting surface of the respective elements distributed across the firstring and the concentric ring substantially coplanar; and an image sensorsupported by the enclosure and arranged to convert reflected lightresponsive to the respective first and second orientations intorespective data assets.
 2. The device of claim 1, wherein the firstorientation is approximately orthogonal to the second orientation. 3.The device of claim 1, wherein light oscillating in the firstorientation is responsive to a respective feature of the first lightemitter.
 4. The device of claim 1, wherein light oscillating in thesecond orientation is responsive to a respective feature of the secondlight emitter.
 5. The device of claim 1, wherein light oscillating inthe first orientation is responsive to a first polarizer located betweenthe first light emitter and a subject-of-interest.
 6. The device ofclaim 1, wherein light oscillating in the second orientation isresponsive to a second polarizer located between the second lightemitter and a subject-of-interest.
 7. The device of claim 1, wherein anillumination power produced by at least one of the first light emitterand the second light emitter is controllably adjusted by modifying abias current.
 8. The device of claim 1, wherein the first light emitterand the second light emitter are arranged circumferentially about thelens housing.
 9. The device of claim 1, wherein the illumination sourcedirects light oscillating in two orientations substantially orthogonalto one another away from the device, the light forming an angle ofincidence with respect to a longitudinal axis of the lens assembly ofless than about 2.5 degrees when reflected by a subject-of-interestseparated by at least one meter from the image-capture device.
 10. Thedevice of claim 1, wherein at least one of the first light emitter andthe second light emitter comprise semiconductors.
 11. The device ofclaim 10, wherein a distance along a plane substantially orthogonal to alongitudinal axis of the lens assembly between nearest neighbors of thesemiconductors is determined by a minimum tolerance associated with asemiconductor manufacturing process.
 12. The device of claim 1, whereinone of the first light emitter and the second light emitter emit lightwith a range of different wavelengths from 390 nm to 700 nm.
 13. Thedevice of claim 1, wherein one of the first light emitter and the secondlight emitter emit light with a range of different wavelengths withwavelengths shorter than 390 nm and/or longer than 700 nm.
 14. Thedevice of claim 1, wherein the first light emitter and the second lightemitter are arranged to prevent emitted light from entering the lenswithout contacting a surface of a subject-of-interest and are furtherarranged with a barrier interposed between the first light emitter andthe second light emitter to prevent emitted light from a first emitterfrom passing through a polarizer filter associated with a second lightemitter and respectively from a second emitter from passing through apolarizer filter associated with a first light emitter.
 15. The deviceof claim 1, further comprising: a controller in communication with theimage sensor and the image-capture device, the controller arranged tocoordinate operation of the image-capture device and the illuminationsource such that an interval between a first exposure of the imagesensor to light oscillating in the first orientation away from theimage-capture device and reflected by a subject-of-interest and a secondexposure of the sensor to light oscillating in the second orientationaway from the image-capture device and reflected by thesubject-of-interest is controlled.
 16. The device of claim 15, whereinthe image sensor is nonplanar.
 17. The device of claim 15, wherein theimage sensor includes hyperspectral sensitive semiconductors.
 18. Thedevice of claim 15, wherein the interval between the first exposure andthe second exposure results in a first raster of image information and asecond raster of image information responsive to substantially the sameimage information.
 19. The device of claim 18, wherein the imageinformation in the first raster and the image information in the secondraster are responsive to substantially the same orientation of theimage-capture device.
 20. The device of claim 15, further comprising: apolarizer positioned between the image sensor and a subject of interest,the polarizer configured substantially orthogonal to light oscillatingin one of the first orientation or the second orientation andsubstantially parallel to light oscillating in the remaining one of thefirst orientation or the second orientation.
 21. The device of claim 15,wherein the controller generates a signal that modifies one of the firstorientation or the second orientation.
 22. An image-capture device,comprising: an enclosure including at least two image sensors; a lens ina lens housing supported by the enclosure; and an illumination sourcethat directs emitted light away from the enclosure, the illuminationsource arranged such that respective emitters surround a perimeter ofthe lens housing, wherein emitted light directed away from the enclosureby the illumination source is orthogonally polarized with respect to apolarization angle of reflected light that intersects at least one imagesensor, wherein the lens receives reflected light from asubject-of-interest and directs the reflected light in a first opticalpath having a first polarizer and in a second optical path having asecond polarizer such that reflected light that traverses the firstpolarizer is substantially orthogonal to reflected light that traversesthe second polarizer, wherein a first image sensor intersecting thefirst optical path captures a first image and a second image sensorintersecting the second optical path captures a second image such thatthe first image and the second image are captured at a first time. 23.The device of claim 22, wherein at least one image sensor intersects thefirst optical path and at least one separate image sensor intersects thesecond optical path.
 24. The device of claim 22, further comprising: abeamsplitter, wherein the first optical path receives transmitted lightthat traverses the beamsplitter and the second optical path receiveslight reflected by the beamsplitter.
 25. The device of claim 22, whereinthe illumination source and lens are arranged to prevent emitted lightfrom entering the lens without contacting a surface of thesubject-of-interest.
 26. The device of claim 22, wherein theillumination source comprises semiconductors arranged about the lenshousing.
 27. An image-capture device, comprising: an enclosure having amounting surface; light emitters supported along the mounting surface,the light emitters directing light in a direction substantiallyorthogonal to the mounting surface, the light oscillating in a firstorientation; a first set of image sensors arranged along the mountingsurface, the first set of image sensors receiving reflected lightoscillating in the first orientation; a second set of image sensorsarranged along the mounting surface, the second set of image sensorsreceiving reflected light oscillating in a second orientationsubstantially orthogonal to the first orientation, a third set of imagesensors arranged along the mounting surface, the third set of imagesensors receiving reflected light oscillating in more than oneorientation, wherein the first set of image sensors and the second setof image sensors are surrounded by respective subsets of the lightemitters.
 28. The device of claim 27, wherein the light emitters areoffset from the first and second sets of image sensors to prevent lightoriginating at the light emitters from directly contacting the first andsecond sets of image sensors.